A&D Weighing GXA-13 Instruction Manual

GXA-13 Density Determination Kit

1WMPD4003565A

© 2017 A&D Company, Limited. All rights reserved.
No part of this publication may be reproduced, transmitted, transcribed, or translated

into any language in any form by any means without the written permission of A&D
Company, Limited.

The contents of this manual and the specifications of the instrument covered by this

manual are subject to change for improvement without any notice and obligation on
the part of the manufacturer.

Contents

1. Introduction ............................................................................................................................................ 2

1.1. Precautions ....................................................................................................................................... 2

2. Packing List ........................................................................................................................................... 3

3. Density Measurement Principle ........................................................................................................... 4

3.1. Density .............................................................................................................................................. 4

3.2. Specific Gravity ................................................................................................................................. 4

3.3. Density Measurement Principle ...................................................................................................... 4

3.4. Density of a Solid .............................................................................................................................. 4

3.5. Density of a Liquid ............................................................................................................................ 4

4. Error Factors .......................................................................................................................................... 5

4.1. Buoyancy of Air ................................................................................................................................. 5

4.2. Temperature of a Liquid ................................................................................................................... 5

4.3. Volume of Float ................................................................................................................................. 5

4.4. Influence of Wire ............................................................................................................................... 5

4.5. Surface Tension ................................................................................................................................ 6

4.6. Bubbles ............................................................................................................................................. 6

5. Measuring the Density of a Solid ......................................................................................................... 8

5.1. Assembling the Kit ............................................................................................................................ 8

5.1.1. Assembling the Kit Using Glass Breeze Break (GXA-10) ....................................................... 9

5.2. Measuring the Density of a Solid ................................................................................................... 10

5.2.1. Density of Water ........................................................................................................................ 10

6. Measuring the Density of a Liquid...................................................................................................... 11

6.1. Assembling the Kit .......................................................................................................................... 11

6.2. Measuring the Density of a Liquid ................................................................................................. 11

7. Density Measurement Using the GX-A／GF-A Balance ............................................................... 12

7.1.1. Preparation Before Measurement (Settings of the Function Table） ................................... 12

7.1.2. Measuring Solid Density (Specific Gravity), Function Table ....................................... 14

7.1.3. Specifying Liquid Density ......................................................................................................... 15

7.1.4. Measuring Liquid Density (Specific Gravity), Function Table ...................................... 16

7.1.5. Specifying Volume of Float ....................................................................................................... 17

8. Frequently Asked Questions and Answers ....................................................................................... 18

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1. Introduction

Thank you for your A&D purchase! This is the instruction manual for the density determination kit.
The density determination kit can be easily used to measure the density of solid or liquid when it is

combined with the following electronic balances.
GX-203A, GX-303A, GX-403A, GX-603A, GX-1003A, GX-1603A,

GF-203A, GF-303A, GF-403A, GF-603A, GF-1003A, GF-1603A
Before using the density determination kit, please read this instruction manual thoroughly.

1.1. Precautions

This density determination kit allows the density or specific gravity of a solid or liquid to be measured.

However, the results of measurements may be affected by various factors that could cause errors,

therefore we cannot guarantee them to be 100 % accurate.
Do not use the density determination kit for measuring the density of chemically active substances.
After using the density determination kit, clean all surfaces to remove rust and oxides.
The balance is precision instrument, so avoid shocks or excessive loads.
To improve measuring accuracy, allow the temperature of liquid (water) and sample (solid) to

equalize to the ambient room temperature and perform measurement in a stable environment.
The breeze break provided with the balance cannot be used with the density determination kit.

To perform an accurate density measurement, use the glass breeze break available as an option

( GXA-10).

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2. Packing List

φ0.2

Float Wire Float hook Thermometer

Density pan stand Beaker stand Beaker Thermometer clamp

Density pan Beaker stand spacer 2 pieces Tweezers

Kit box

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3. Density Measurement Principle

3.1. Density

Density means the amount of mass of a sample per unit volume. ( Unit [g/cm3] and others )

ρ = ρ: Density [g/cm3] M: Mass [g] V: Volume [cm3]

3.2. Specific Gravity

Specific gravity means the ratio of the density of a sample to the density of pure water (with the

same volume as that of the sample) at 4 °C at 1013.25 hPa.

ρ = ρ: Specific gravity [ No unit ] M: Mass [g] V: Volume [cm3]
ρ4: Density of water at 4 [°C], 0.99997 [g/cm3]  1.000 [g/cm3]

M

V

M

V•ρ4

3.3. Density Measurement Principle

The GXA-13 combined with an authorized balance can measure the density of a sample based on

the Archimedes’ principle.

Archimedes’ Principle of Density Measurement
A body immersed in a liquid (gas) is subject to an upward force equal to the weight of the
liquid (gas) it displaces. The upward force is buoyancy.

3.4. Density of a Solid

The density of a solid can be obtained according to the sample weight in air, sample weight in liquid

and the density of the liquid.

ρ = ×ρ0 ρ: Density of sample [g/cm3] A: Sample weight in air [g]
ρ0: Density of liquid [g/cm3] B: Sample weight in liquid [g]

A

A - B

3.5. Density of a Liquid

The density of a liquid can be obtained according to the weight of the float in air, the weight of the

float in a liquid, and the known volume of the float.

ρ = +d ρ: Density of liquid [g/cm3] A: Weight of the float in air [g]
V: Volume of the float [cm3] B: Weight of the float in liquid [g]
d: Density of air ( approximately 0.001 [g/cm3] )

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A - B

V

4. Error Factors

There are several error factors that may affect the accuracy of a density measurement.

4.1. Buoyancy of Air

When the liquid density is measured, an upward force, 0.0010 to 0.0014 [g/cm3], is exerted in

proportion to the volume of the liquid. The buoyancy in air per 1 [cm3] is found by:

d = × d: Air density [g/cm3] t: Air temperature [°C]
P: Air pressure [hPa]

When obtaining measurement results down to the third decimal place, 0.001 [g/cm3] is added to

the measured value to compensate for an error in air density.

0.0012932

1+0.0036728×t

P

1013.25

4.2. Temperature of a Liquid

When taking a density measurement using a liquid, the density measurement will change depending on

the temperature. Obtain the density of a liquid by comparing its temperature with the values in "Table 1

Temperature and Density of Water" for distilled water or provided in other reference documents for

other liquids.

4.3. Volume of Float

The tolerance of the measured value of the volume of the float is ±0.01 [cm3].

4.4. Influence of Wire

When a solid sample is placed on the density pan for measurement, which is immersed in a liquid,

the liquid surface position rises. At this time, the wire (1 mm) connecting the upper and lower pans

is subject to the buoyancy whose magnitude is equal to the weight of the raised liquid. 1 mm raise of

the liquid surface exerts a buoyancy of approx. 0.8 mg to the wire. To minimize a measurement error

caused by the buoyancy, adjust the sample size so that it will not raise the liquid surface, or perform

a mathematical correction.
When measuring the density of a liquid, the float-suspending wire (2 mm) immersed in the liquid

affects the measurement. Immersing the wire by 10 mm exerts a buoyancy of approx. 0.3 mg to the

wire. However, this buoyancy can be ignored because it is divided by the volume of the float when

the density of the liquid is obtained.

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4.5. Surface Tension

When the density of a solid is measured, a force of approx. 5 mg (surface tension) is applied to the

density pan, between the wire (1 mm) of the density pan and the surface of the liquid.
The surface tension can be reduced to approx. 1 mg by adding a surfactant (for example, a water

droplet preventive solution as used for developing photographs). Adding 0.1 mL (1.2 [g/cm3]

density) of a surfactant to 200 mL of water will increase the density of the water by approx. 0.0001

[g/cm3].
When the density of a liquid is measured, a force of about 1 mg is exerted by the wire of 0.2 mm in

diameter. However, this force can be ignored because it is divided by the volume of the float.

4.6. Bubbles

The buoyancy of a bubble of 1 mm in diameter is approx. 0.5 mg. Stickiness of bubbles depends on

the shape and material of a sample. Make measurements considering the characteristic of bubbles.
When the density of a solid is measured, we recommend adding a surfactant to reduce the influence

of surface tension and bubbles.

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